藤本植物Potentilla reptans叶对风和遮阴的响应

生长在一个密集植物群中的植株由于相互遮蔽而不可能对风的影响做出反应,因为这样的环境条件(有限的光资源)对由风导致的矮小表型植株的生长是不利的。为弄清在密集植物群体中生长的植株对风的响应,利用藤本植物Potentilla reptans的10种基因型做实验材料,在温室条件下(光照强度为日光照的50%,红光/远红光=1.2)模拟冠层遮阴(相当于15%的日光照,红光/远红光=0.3),研究了藤本植物叶对风的响应。结果表明,Potentilla reptans的10种基因型植株在冠层遮阴下(低的红光/远红光)都表现出典型的避阴生长响应:较少的叶(叶生物量少),长而细但硬度系数高(higher Young's modulus)的叶柄;而受风影响的植株,无论遮阴或不遮阴,其植株的叶相对较多,叶柄短、粗且柔韧性强(lower Young's modulus),说明Potentilla reptans叶对风的响应并未因遮阴而被压抑,其可塑性变化不过是对复杂生境做出的一种生长权衡:尽可能增强抗风能力(矮壮)和获取最大光能(足够高而避免被遮光),即保证在存活下去的前提下获取最大的生长效率。

Differential response to wind and shade in mother leaf of Potentilla reptans

Responses to mechanical stress(such as wind)should be suppressed in dense vegetation since the resultant shorter stature would lead to low fitness.However,this point has been debated,i.e.it has been argued that in dense vegetations a sensitivity to mechanical stress might provide an additional cue to shade avoidance.For 10 different genotypes of the clonal plant Potentilla reptans,the effects of shade(15% of daylight with a red:far red ratio,R/FR of 0.3 vs.50% daylight and R/FR of 1.2)and wind(0 or 40 daily brushes with a duster)on the mother leaf properties were investigated.All genotypes exhibited typical"shade avoidance" responses under shade,such as the production of fewer leaves with longer petioles,reductions in petiole diameter,and the production of more rigid petiole tissue(petioles with a higherYoung'modulus).Wind-treated plants produced more leaves with shorter and thicker petioles made of nlore flexible tissue (lower Young's modulus).All responses to wind are different from responses to shade.Interestingly the responses to wind in leaf of Potentilla reptans were opposite in nature to the responses to light.